1. Field of the Invention
The present invention relates to a vehicle-generator output voltage control apparatus for regulating an output voltage of a generator mounted on a vehicle such as a passenger car or a truck.
2. Description of Related Art
There is known a vehicle-generator output voltage control apparatus having a signal output terminal (generally called an FR-terminal) for outputting a signal indicative of a power generation state of a vehicle generator, as disclosed, for example, in Japanese Utility Model Publication No. 6-19359. To perform an output voltage control, this vehicle-generator output voltage control apparatus uses a pulse-like voltage signal appearing at one end of a field coil of a vehicle generator and inputted therein through an F-terminal which is one of its signal input terminals.
Also, there is known a vehicle-generator output voltage control apparatus having a function of changing an output voltage of a vehicle generator between two different levels, as disclosed, for example, in Japanese Patent Application Laid-open No. 3-173325. This vehicle-generator output voltage control apparatus is configured to set the output voltage of the vehicle generator at a low level at the time of starting a vehicle engine, as a result of which the vehicle generator stops its power generating operation. This makes it possible to reduce the power generation torque of the vehicle generator, to thereby stabilize an engine rotational speed during an engine starting period.
Incidentally, there is a need to provide a vehicle-generator output voltage control apparatus such as disclosed in Japanese Utility Model Publication No. 6-19359 with the function as disclosed in Japanese Patent Application Laid-open No. 3-173325. However, to meet this need, it is necessary to additionally provide such a vehicle-generator output voltage control apparatus with a terminal for receiving a power generation stop command from outside, and a cable to be connected to this terminal. Since this requires significant design changes of the vehicle-generator output voltage control apparatus and the vehicle generator, their production costs increase, and their sizes also increase.